Black hole devouring star for a decade detected

February 7, 2017, 9:27 PM IST

Washington: Astronomers have detected a giant black hole that ripped apart a star and then gorged on its remains for an unusually long time — about a decade, which is more than ten times longer than any observed episode of a stars death by black hole.

Researchers made this discovery using data from NASA’s Chandra X-ray Observatory and Swift satellite as well as European Space Agency’s XMM-Newton.

The trio of orbiting X-ray telescopes found evidence for a “tidal disruption event” (TDE), wherein the tidal forces due to the intense gravity from a black hole can destroy an object — such as a star — that wanders too close.

During a TDE, some of the stellar debris is flung outward at high speeds, while the rest falls toward the black hole. As it travels inwards to be ingested by the black hole, the material heats up to millions of degrees and generates a distinct X-ray flare.

“We have witnessed a star’s spectacular and prolonged demise,” said lead researcher Dacheng Lin from the University of New Hampshire in Durham, New Hampshire.

“Dozens of tidal disruption events have been detected since the 1990s, but none that remained bright for nearly as long as this one,” Lin noted.

The extraordinary long bright phase of this event spanning over ten years means that among observed TDEs this was either the most massive star ever to be completely torn apart during one of these events, or the first where a smaller star was completely torn apart, said the study published in the journal Nature Astronomy.

The X-ray source containing this force-fed black hole, known by its abbreviated name of XJ1500+0154, is located in a small galaxy about 1.8 billion light years from Earth.

The sharp X-ray vision of Chandra data showed that XJ1500+0154 is located at the centre of its host galaxy, the expected location for a supermassive black hole.

The X-ray data also indicated that radiation from material surrounding this black hole has consistently surpassed the so-called Eddington limit, defined by a balance between the outward pressure of radiation from the hot gas and the inward pull of the gravity of the black hole.